Stephen LaLumondiere

Observation of single event upsets in analog microcircuits

Selected analog devices were tested for heavy-ion-induced single event upset (SEU). The results of these tests are presented, likely upset mechanisms are discussed, and standards for the characterization of analog upsets are suggested. The OP-15 operational amplifier, which was found to be susceptible to SEU in the laboratory, has also experienced upset in space. Possible strategies for mitigating the occurrence of analog SEUs in space are also discussed. >

Correlation of picosecond laser-induced latchup and energetic particle-induced latchup in CMOS test structures

We show that the thresholds for picosecond (psec) laser pulse-induced latchup and energetic particle-induced latchup are well correlated over a range of bulk CMOS test structures designed to be susceptible to latchup. The spatial length of the latchup-sensitive node of the test structures covers a range of values that commonly occur in bulk CMOS devices. The accuracy of this correlation implies that laser-induced latchup can be used for hardness assurance and, under the proper conditions, can be an accurate predictor of latchup threshold linear energy transfer (LET) for most bulk CMOS devices.

Single event upset (SEU) sensitivity dependence of linear integrated circuits (ICs) on bias conditions

The single event upset (SEU) sensitivity of certain types of linear microcircuits is strongly affected by bias conditions. For these devices, a model of upset mechanism and a method for SEU control have been suggested.

Comparison of SETs in bipolar linear circuits generated with an ion microbeam, laser light, and circuit simulation

Generally good agreement is obtained between the single-event output voltage transient waveforms obtained by exposing individual circuit elements of a bipolar comparator and operational amplifier to an ion microbeam, a pulsed laser beam, and circuit simulations using SPICE. The agreement is achieved by adjusting the amounts of charge deposited by the laser or injected in the SPICE simulations. The implications for radiation hardness assurance are discussed.

Laser-induced and heavy ion-induced single-event transient (SET) sensitivity measurements on 139-type comparators

We have measured the single-event transient (SET) response for a number of 139-type comparators with differing topologies. In this paper, we present the results from pulsed laser measurements on a number of different 139-type devices, as well as heavy ion measurements on a new RM139 device from NSC. Devices tested with the laser included the HS-139RH, PM139, LM139 and a more recent version of LM139 from NSC. We discuss the effects of different device topologies on SET sensitivity. Our results agree qualitatively with SPICE model calculations of LM139s by Johnston et al.

Narrow band gap (1 eV) InGaAsSbN solar cells grown by metalorganic vapor phase epitaxy

Heterojunction solar cell structures employing InGaAsSbN (Eg ∼ 1 eV) base regions are grown lattice-matched to GaAs substrates using metalorganic vapor phase epitaxy. Room temperature (RT) photoluminescence (PL) measurements indicate a peak spectral emission at 1.04 eV and carrier lifetimes of 471–576 ps are measured at RT from these structures using time-resolved PL techniques. Fabricated devices without anti-reflection coating demonstrate a peak efficiency of 4.58% under AM1.5 direct illumination. Solar cells with a 250 nm-thick InGaAsSbN base layer exhibit a 17% improvement in open circuit voltage (Voc), 14% improvement in fill factor, and 12% improvement in efficiency over the cells with a thicker (500 nm-thick) base layer.

Impact of thermal annealing on bulk InGaAsSbN materials grown by metalorganic vapor phase epitaxy

Two different thermal annealing techniques (rapid thermal annealing (RTA) and in-situ post-growth annealing in the metalorganic vapor phase epitaxy (MOVPE) chamber) were employed to investigate their impact on the optical characteristics of double-heterostructures (DH) of InGaAsSbN/GaAs and on the performance of single-junction solar cell structures, all grown by MOVPE. We find that an optimized RTA procedure leads to a similar improvement in the photoluminescence (PL) intensity compared with material employing a multi-step optimized anneal within the MOVPE reactor. Time-resolved photoluminescence techniques at low temperature (LT) and room temperature (RT) were performed to characterize the carrier dynamics in bulk InGaAsSbN layers. Room temperature carrier lifetimes were found to be similar for both annealing methods, although the LT-PL (16 K) measurements of the MOVPE-annealed sample found longer lifetimes than the RTA-annealed sample (680 ps vs. 260 ps) for the PL measurement energy of 1.24 eV. InGaAsSbN-based single junction solar cells processed with the optimized RTA procedure exhibited an enhancement of the electrical performance, such as improvements in open circuit voltage, short circuit current, fill factor, and efficiency over solar cells subjected to the in-situ MOVPE annealing technique.

Carrier dynamics in MOVPE-grown bulk dilute nitride materials for multi-junction solar cells

Dilute nitride materials with a 1eV band-gap lattice matched to GaAs substrates are attractive for high-efficiency multi-junction solar cells. Carrier lifetime measurements are crucial in optimizing material growth and p-i-n field-aided carrier-extraction-device design. One research group has reported carrier lifetimes of MBE-grown bulk InGaNAsSb materials, but there has been no report of carrier lifetime measurements from bulk InGaNAsSb grown by MOVPE. In this study, we report the growth of bulk InGaNAsSb by MOVPE and the first carrier lifetime measurement from MOVPE-grown bulk InGaNAsSb materials with Eg= 1.0 - 1.2eV at 300K. We studied carrier dynamics in MOVPE-grown bulk dilute nitride materials nominally lattice matched to GaAs (100) substrates: 1μm thick In0.035GaN0.025As (Eg= 1.0eV at 300K) and ~0.2μm thick In(0.05-0.07)GaN(0.01-0.02)AsSb(0.02-0.06) layers (Eg= 1.2eV at 300K). Both structures are fully strained. The incorporation of N in InGaNAs leads to degradation in photoluminescence efficiency, but prior studies indicate the addition of Sb in MBE-grown InGaNAsSb improved the PL efficiency. Two-step post-growth thermal annealing processes were optimized to obtain maximum PL efficiencies that yielded a typical blue shift of 50 and 30meV for InGaNAs and InGaNAsSb, respectively. We employed a streak camera to measure carrier lifetimes from both as-grown and thermally annealed samples. Carrier lifetimes of <30psec were obtained from the InGaNAs samples, whereas carrier lifetimes of up to ~150psec were obtained from the InGaNAsSb samples. We discuss possible reasons for short carrier lifetimes measured from MOVPE-grown InGaNAs(Sb) materials.

A TID and SEE Radiation-Hardened, Wideband, Low-Noise Amplifier

We have developed a radiation-hardened, highly linear, wideband, low-noise amplifier (LNA) with programmable gain to serve as the front-end of a plasma-wave instrument for satellite-based electric-field measurements of very low frequency (VLF) phenomena in the Van Allen radiation belts. Fabricated in a commercial 0.25-mum silicon-germanium BiCMOS process, this ASIC leverages radiation-hardness-by-design techniques at the topological, implementation, and layout levels to maintain 75-dB spurious-free dynamic range (SFDR) over nearly four decades of frequency, from 100 Hz to 1 MHz, for both proton and gamma-ray total ionizing dose (TID) exposures up to 1000 krad(Si). Single-event effect (SEE) testing via pulsed laser confirms negligible latchup sensitivity and suppression of single-event transients (SETs) at the output for beam energy LET equivalents in excess of 100MeV-cm2 /mg in even the most sensitive regions of the die

Physics of failure investigation in high-power broad-area InGaAs-AlGaAs strained quantum well lasers

Continued improvements in broad-area InGaAs-AlGaAs strained quantum well (QW) lasers have led to unprecedented performance characteristics in these lasers including optical output powers of over 20 W and power conversion efficiencies of over 70% under CW operation. Catastrophic optical mirror damage (COMD) is responsible for failures in (Al)GaAs QW lasers, but InGaAs-AlGaAs strained QW lasers with optimized facet passivation predominantly fail by catastrophic optical bulk damage (COBD). Since COBD is relatively a new failure type, it requires physics of failure investigation to understand its root causes and then develop COBD-free lasers for high reliability applications including potential satellite systems. We recently proposed a model for degradation mechanism responsible the COBD process and this paper further investigates the root causes of COBD in the lasers using various failure mode analysis techniques. We investigated reliability and degradation mechanism in MOCVD-grown broad-area InGaAs-AlGaAs strained QW single emitters. During entire accelerated life-tests of the lasers we studied, time resolved electroluminescence (TR-EL) techniques were employed to observe formation of a hot spot and subsequent formation and progression of dark spots and dark lines through windowed n-contacts.